Pages I - II
doi: 10.4274/jems.2021.60134 Page 156
Abstract | Full Text PDF
|ORIGINAL RESEARCH (AR)|
|3.||A Comprehensive Evaluation of Yacht Charter Service Concept: Influence of Voyager-to-Voyager Interaction on Service Satisfaction|
Neslihan Paker, Osman Gök
doi: 10.4274/jems.2021.94834 Pages 157 - 167
The study attempts to evaluate yacht charter service attributes considering the service quality, customer satisfaction, and loyalty three-leg framework. Besides visited destinations, the service concept is enlarged with social servicescape dimensions of interaction quality and customer similarity for a holistic approach. A self-administered questionnaire was provided to 359 customers, and the relationships in the research model were tested via structural equation modeling. The results showed that satisfaction depends on the interaction quality, which is strongly related to the similarity between other customers, as well as the quality of the service elements and the attractiveness of the visited destination. This study presents a pioneering research attempt focusing on the influence of customer-to-customer interaction and customer similarity on yacht charter services. Findings of the study provide a theoretical contribution, highlighting the importance of customer-to-customer interaction for service appraisals of customers. Theoretical and practical implications for interaction-dominant services are discussed.
|4.||A Sequential Solution with MCDM Methods at the Motor-Yacht Construction Problem|
Ganimet Nilay Yücenur
doi: 10.4274/jems.2021.88155 Pages 168 - 176
Yachting is quite popular in recent years and it is defined as an entertainment and vacation industry in the sea. The yachting industry as parallel to the world economy is developing rapidly in financial, industrial, and physical spaces in the world and in Turkey as well. With this development, yachting provides foreign currency inflow to Turkey in the tourism sector as well as in the construction industry according to the Turkish Statistical Institutes data. Turkey is greatly known in the European yacht and boat market particularly in terms of engine manufacture and specialization, low labor cost, and quality advantages. This study is aimed to determine a suitable shipyards city to carry out a 30-meter motor yacht. In this research study, a model was suggested for selecting the appropriate shipyard for motor-yacht construction with a proposed solution methodology. In the research methodology, 15 criteria were determined for evaluating 4 shipyards that have different properties and are located in different cities of Turkey. In the first phase of the solution, SWARA was used to obtain the importance weights of the criteria. In the second phase of the solution, alternatives were evaluated with COPRAS according to the calculated importance weights. The proposed model and solution methodology were conducted through an explanatory sample.
|5.||Effects of Exhaust Backpressure Increment on the Performance and Exhaust Emissions of a Single Cylinder Diesel Engine|
Yiğit Gülmez, Güner Özmen
doi: 10.4274/jems.2021.25582 Pages 177 - 191
Exhaust gas aftertreatment systems and exhaust gas waste heat recovery systems are main solutions to decrease the environmental impact and increase the efficiency of diesel engines. However, any system installed on the exhaust pipe of diesel engines is a source of exhaust backpressure. Moreover, increasing the exhaust backpressure has negative effects on the performance and environmental impact of diesel engines. The study aims to investigate the negative impacts of exhaust backpressure increment on performance indicators, fuel consumption and exhaust emissions of a diesel engine. The experimental study was performed on a test bench comprising a single cylinder diesel engine, a dynamometer and various measurement equipment. The backpressure was increased by adding various sized orifices on the exhaust pipe of the test engine and the test engine was run under six different engine loads at an engine speed of 1600 rpm. Subsequently, the impacts of backpressure increment on the brake specific fuel consumption (BSFC), brake thermal efficiency, volumetric efficiency, mean effective pressures, mechanical efficiency, and exhaust emissions were determined. The study results showed that backpressure increment causes retarding of combustion phases up to a crank angle of 4°, decrease in the indicated mean effective pressure, and decrease in the peak cylinder pressure from 78.36 to 70.7 bar at the maximum available engine load. From fuel consumption perspective, backpressure increment caused an increase in the BSFC approximately up to 3.29% at 24.66 kPa backpressure. On the other hand, the results showed that increasing the backpressure caused a significant increment in the pumping mean effective pressure and a remarkable decrease in the volumetric efficiency. The findings of this study have significant implications for evaluating the negative impacts of any system installed on the exhaust pipe of a diesel engine.
|6.||Numerical Self-Propulsion Assessment of a Generic Submarine Model at Various Forward Speeds|
doi: 10.4274/jems.2021.24654 Pages 192 - 199
In this study, we use computational fluid dynamics (CFD) to investigate the self-propulsion characteristics of a submarine model. Predicting a marine vehicles self-propulsion features, and as a result, determining the thrust force required to drive the ship with a constant forward speed is critical for the propulsive system and main engine selection. A Reynolds-Averaged-Navier-Stokes Equations based numerical methodology has been applied to the flow field around the Defense Advanced Research Projects Agency suboff geometry to predict the selfproportion characteristics of a marine vehicle. First, the models self-propulsion characteristics were determined for a relatively lower hull speed (5.35 knots), and the results were compared with those of other studies and experiments. The study was then extended to include higher forward speeds ranging from 5.93 to 17.79 knots. The results reveal that the propeller rotation rate at the models self-propulsion point rises as the vessel speed and the power requirement increase. Similarly, the advance coefficient remains nearly unaffected by the Froude Number. The resistance components, propulsion characteristics, flow field surrounding the model, and the wake structure in the propeller slipstream were also evaluated for the determined self-propulsion points.
|7.||Analytical and Numerical Analysis of the Strength Performance of a Novel Ship Construction Profile|
Ahmet Taşdemir, Serkan Nohut, Mehmet Akman
doi: 10.4274/jems.2021.87049 Pages 200 - 209
Construction profiles in different shapes such as bulb flats, tees, channels, and angles are widely used in the shipbuilding industry. During the ship construction process, these conventional profiles are joined to the plates as stiffeners and are dimensioned according to class rules. This article investigates the structural performance of a novel construction profile, the so-called TP profile, that can be used in the hull construction of ships and of which form is inspired by the human bone geometry. The cross-sectional area and the weight of the TP profile are designed to be equal to those of the conventional HP profile and commercial T profile. Strength performances of these profiles are compared via analytical and numerical analyses. The plate joint profiles are modeled under various loading and boundary conditions and the finite element method is used for the calculation of stress components and deflections. The TP profile has a high potential to be used in the shipbuilding industry.
|8.||An Extended Event Tree Risk Analysis Under Fuzzy Logic Environment: The Case of Fire in Ship Engine Room|
Ahmet Lutfi Tunçel, Emre Akyüz, Özcan Arslan
doi: 10.4274/jems.2021.93685 Pages 210 - 220
Ship engine room fire is one of the major dangers that threaten the safety of the ships. An effective firefighting in the engine room is critical to prevent possible destructive consequences on-board ship. Fire detection and firefighting systems, which are designed for an effective fire prevention on-board ship, need to work flawlessly. In order to achieve this, the deficiencies of the designed systems must be determined and necessary control actions must be taken. In this study, failure probabilities of fire detection and firefighting systems on-board ship is calculated by event tree analysis and fuzzy logic environment. The possible consequences that may be encountered in case the systems fail under various scenarios are determined. Solutions have been proposed in order to minimize the risk that may arise by reducing the failure probability of each system. The outcome of this paper will be utilised by safety engineers, shipping companies and safety inspectors to prevent potential engine room fires.